JPH06123414A - Incinerator and incinerating method - Google Patents

Abstract

PURPOSE:To reduce exhaust of a decomposition-resistant organic chlorine compound such as dioxin by generating turning and swirling flows of a combustion gas of incinerated matters in a secondary combustion chamber. CONSTITUTION:A combustion gas of incinerated matters produced from matters thrown into a primary combustion chamber 10 to be incinerated is introduced into a secondary combustion chamber 13 through a flue 14. Since the center of the flue 14 is eccentric to the center of the cross section of the secondary combustion chamber 13, a turning flow of the combustion gas of the incinerated matters is generated in the secondary combustion chamber 13. Moreover, the combustion gas of the incinerated matters flows to a discharge port 16 through a straightening plate 20 provided at the lateral end face of the secondary combustion chamber 13, and therefore the radius of turning of the turning flow of the combustion gas of the incinerated matters lessens gradually by the effect of the inside diameter of the straightening plate 20. In other words, the angular velocity of turning of the turning flow of the combustion gas of the incinerated matters becomes large gradually by a contracting action of the straightening plate 20 and the gas becomes a strongly swirling flow. On the occasion, the strength of the swirling flow of the combustion gas of the incinerated matters increases as the inside diameters of the fule 14 and the straightening plate 20 decrease.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an incinerator for municipal solid waste and industrial wastes, and in particular, improves combustion in a secondary combustion chamber to improve combustibility and to develop a persistent organic chlorine compound such as dioxins. It relates to an incinerator that decomposes.

[0002]

2. Description of the Related Art The generation of dioxins and the like in an incinerator for municipal waste and industrial waste is caused by CO in the incinerator combustion exhaust gas.
There is a strong positive correlation with the concentration, and CO
It is estimated that the concentration of dioxins increases as the concentration increases. In the guidelines for prevention of dioxin generation, which was announced by the Environment Improvement Division, Ministry of Health and Welfare, Ministry of Health and Welfare in December 1990, the CO concentration of incinerator combustion exhaust gas was used as an index of dioxin generation.

On the other hand, conventionally, a vertical two-stage incinerator has been used as an incinerator for municipal waste and industrial waste, particularly as a small incinerator. For example, various smokeless refuse incinerators described in Japanese Patent Publication No. 45-12638. The following types have been proposed. The configuration of the conventional vertical two-stage incinerator will be described in detail with reference to FIGS. FIG. 5 is a front view of a conventional vertical two-stage incinerator, and FIG. 6 is a sectional view taken along line BB of FIG.

In FIGS. 5 and 6, an incinerator insertion door 3 and a lid 2 are openably and closably attached to one end of a primary combustion chamber 1 having a cylindrical shape, and an upper combustion for supplying combustion air is attached to the other end. An air vent 8 is provided. Further, a lower combustion air port 9 for supplying combustion air is provided in the hearth of the primary combustion chamber 1. A secondary combustion chamber 4 is installed above the primary combustion chamber 1 to gasify and burn the incinerator combustion exhaust gas so as to eliminate smoke. The primary combustion chamber 1 is connected via a flue 5 to the secondary combustion chamber 1. Is in communication with. The secondary combustion chamber 4 is provided with a burner 6 for supplying high-temperature gas or flame and a chimney 7 for discharging combustion exhaust gas of incineration material.

In the conventional vertical two-stage incinerator configured as described above, when the incineration object input door 3 is opened and the incineration object is placed on the hearth of the primary combustion chamber 1, the incineration object is generated. Heated by the flame of a burner (not shown) and dried over time,
Combustion and post combustion proceed. Then, when the incineration object burns, an incineration object combustion exhaust gas is generated, and the incineration object combustion exhaust gas reaches the secondary combustion chamber 4 through the flue 5, where the burner 6 burns the incineration object. The unburned portion of the product combustion exhaust gas is burned and discharged from the chimney 7 to the outside of the system in a smokeless state.

[0006]

However, it was feared that these conventional vertical two-stage incinerators would not be able to obtain a sufficient effect in reducing the persistent chlorine compounds such as dioxins. That is, in the above-mentioned conventional vertical two-stage incinerator, in the secondary combustion chamber 4, a part of the unburned gas containing CO, hydrocarbons, etc. is discharged without being decomposed, and the dioxin generated in the incinerator is discharged. Relatives are discharged in relatively large quantities without being decomposed. Also, even if it undergoes thermal decomposition, it is not completely decomposed to carbon dioxide, it stops in a partially oxidized state, and unburned organic carbon content exists in the unburned gas, so temperature conditions in the exhaust gas treatment process in the latter stage, etc. As a result, dioxin is regenerated again.

The combustion exhaust gas from the incineration material is composed of unburned gas containing CO, hydrocarbons and the like, and combustion gas containing a relatively large amount of oxygen. In order to completely decompose carbon dioxide in an unburned gas containing CO, hydrocarbons and the like in the secondary combustion chamber, the secondary combustion chamber must be (1) in a high temperature atmosphere (800-1
000 ° C.), (2) a sufficient retention time for decomposition, and (3) a good mixed state of unburned gas and air are essential conditions. Particularly in the case of a high temperature gas, the viscosity of the gas becomes significantly higher than that at room temperature, so the mixing of unburned gas with air in (3) is important.

An object of the present invention is to solve the above-mentioned problems and to provide an incinerator capable of reducing the emission of hardly decomposable organic chlorine compounds such as dioxins to the utmost limit.

[0009]

The present invention has a burner input door and a burner, a primary combustion chamber to which combustion air is supplied from combustion air supply means, and a burner. An exhaust port that connects to a flue or chimney communicating with the atmosphere is provided,
In an incinerator in which a secondary combustion chamber having a cylindrical shape is vertically connected through a flue, the center of the flue that connects the primary combustion chamber and the secondary combustion chamber is the center of the cross section of the secondary combustion chamber. Eccentric with respect to the incinerator combustion exhaust gas discharged from the primary combustion chamber is introduced in the tangential direction of the secondary combustion chamber, and an approximately circular opening is provided in the vicinity of the exhaust gas outlet of the secondary combustion chamber. The opening area a has a straightening vane whose ratio a / A to the cross-sectional area A of the secondary combustion chamber is 0.15 to 0.5. The dimensionless number R defined by the exhaust gas inflow velocity V (m / s), the secondary combustion chamber diameter D (m), and the incinerator combustion exhaust gas kinematic viscosity ν (m2 / s)
(DV / ν) is 20,000 or more.

[0010]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a cross-sectional view of the incinerator of the present invention, FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1, and FIG. 3 is a concept showing the behavior of incinerator exhaust gas in the secondary combustion chamber 13 of the incinerator of the present invention. Figure,
FIG. 4 is a diagram showing the combustion efficiency in the present invention, and is a diagram showing the relationship between the CO concentration of incinerator combustion exhaust gas and the dimensionless number R.

In FIGS. 1 and 2, an incineration object loading door 12 and a lid 11 are openably and closably attached to one end of the primary combustion chamber 10, and an upper combustion air port 18 for supplying combustion air is provided at the other end. Further, a lower combustion air port 19 for supplying combustion air is provided in the hearth of the primary combustion chamber 10. A secondary combustion chamber 13 is installed above the primary combustion chamber 10 for gasifying and burning the incineration material combustion exhaust gas to eliminate smoke. The primary combustion chamber 10 is connected via a flue 14. Communicate with.

The secondary combustion chamber 13 has a cylindrical shape, the flue 14 is eccentric with respect to the center of the cross section of the secondary combustion chamber 13, and the incinerator combustion exhaust gas from the primary combustion chamber 10 is eccentric. Are arranged so that they can be introduced in the tangential direction of the secondary combustion chamber 13. Further, in the secondary combustion chamber 13, a burner 15 for supplying high-temperature gas or a flame is provided on one end face relatively close to the flue 14, and a flow straightening plate 2 is provided on the other end face in the vicinity of an exhaust port 16 for burning incineration material combustion exhaust gas.
0 is provided and communicates with the flue 17 through the outlet 16.

In the embodiment shown in FIGS. 1 and 2, an example is shown in which the incineration object loading door 12 is opened and closed by manual operation to throw in dust, but a function of automatically opening and closing via a cylinder or the like is added. , May be automated. Further, the automated incinerator loading door may be arranged at the other end of the primary combustion chamber 10, and an incinerator loading device may be installed in front of the incinerator loading door.

Next, with reference to FIGS. 1 to 3, the combustion state of the incinerator and the flow of the incinerator combustion exhaust gas in the incinerator of the present invention configured as described above will be described. The material to be incinerated in the primary combustion chamber 10 is heated by the flame of a burner (not shown) arranged in the primary combustion chamber 10, and progresses over time such as drying, burning, and post-combustion. At that time, the combustion air is supplied to the incineration object through the combustion air supply means. When the incineration object burns, incineration object combustion exhaust gas is generated, and the incineration object combustion exhaust gas is introduced into the secondary combustion chamber 13 via the flue 14. Since the center of the flue 14 is eccentric with respect to the center of the cross section of the secondary combustion chamber 13, a swirl flow of the incineration material combustion exhaust gas is generated in the secondary combustion chamber 13. Further, the combustion exhaust gas of the incineration object flows to the discharge port 16 through the flow straightening plate 20 on the lateral end surface of the secondary combustion chamber 13, so that it is affected by the inner diameter of the flow straightening plate 20, and the swirling flow of the combustion exhaust gas of the incineration object. The turning radius of is gradually reduced. That is, due to the contracting action of the straightening vanes 20, the swirling angular velocity of the swirling flow of the incineration material combustion exhaust gas gradually increases and becomes a violent swirl flow. At this time, as the inner diameters of the flue 14 and the rectifying plate 20 become smaller, the intensity of the swirl of the incineration material combustion exhaust gas increases.

Next, the combustion effect of the present invention will be described with reference to FIG. The figure shows the combustion efficiency in the present invention, and is a diagram showing the relationship between the CO concentration of the combustion exhaust gas from the incineration object and the dimensionless number R. In the figure, the horizontal axis represents the dimensionless number R, and the vertical axis represents the CO concentration of the incinerator combustion exhaust gas. Further, in the same figure, for comparison, the results according to the related art are also shown. From the results shown in the figure, in both the present invention and the conventional case, as the dimensionless number R increases, the CO of the incinerator combustion exhaust gas is increased.
It can be seen that although the concentration is remarkably reduced, it tends to be saturated in a region where the dimensionless number R exceeds 40,000. In the present invention, the CO concentration of the combustion exhaust gas of the incineration object is saturated at 35 to 40 ppm, and conventionally 100 ppm is saturated. Further, comparing the present invention with the conventional one, it can be seen that the CO concentration of the incinerator combustion exhaust gas in the present invention is remarkably low. Further, in the present invention, the target value of 100 ppm or less of the mechanized batch furnace defined by the guidelines for prevention of generation of dioxins is set to A = 2.
It has reached over 10,000.

[0016]

EFFECTS OF THE INVENTION In the secondary combustion chamber, the swirling and swirling flow of the combustion exhaust gas of the incineration material greatly accelerates the stirring and mixing of the unburned gas and the combustion air, and the gas of the unburned gas As a result of the progress of chemical combustion, the concentrations of CO and hydrocarbons contained in the incinerator combustion exhaust gas discharged from the secondary combustion chamber can be significantly reduced. Furthermore, it is possible to decompose persistent organic chlorine compounds such as dioxins to the maximum. Further, as described above, in the secondary combustion chamber, by swirling and swirling the flow of the combustion incinerator combustion exhaust gas, the short path of the combustion incinerator combustion exhaust gas and the low temperature region (8
(Less than 00 ° C.) can be suppressed, and as a result, it is effective in establishing a high temperature atmosphere and ensuring decomposition time in the secondary combustion chamber. As is clear from the above description, the present invention can significantly reduce the CO concentration in the combustion exhaust gas of incineration materials as compared with the conventional vertical two-stage incinerator, and the dioxin announced by the Ministry of Health and Welfare in December 1990. It is possible to provide an incinerator that can comply with guidelines such as the prevention of generation of waste.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an incinerator of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a conceptual diagram showing the behavior of incinerator combustion exhaust gas in the secondary combustion chamber 13 of the incinerator of the present invention.

FIG. 4 is a diagram showing the combustion efficiency in the present invention, showing the relationship between the CO concentration of the combustion exhaust gas from the incineration object and the dimensionless number R.

FIG. 5 is a front view of a conventional vertical two-stage incinerator.

6 is a sectional view taken along line BB of FIG.

[Explanation of reference symbols] 10 primary combustion chamber 13 secondary combustion chamber 14 flue 15 burner 16 discharge port 17 flue 20 straightening plate

Claims (3)

[Claims] 1. A flue that has a burner for injecting a material to be incinerated and a burner, has a burner and a primary combustion chamber to which combustion air is supplied from combustion air supply means, and communicates with the atmosphere. Alternatively, in an incinerator in which an exhaust port connected to a chimney is provided and a secondary combustion chamber having a cylindrical shape is vertically connected via a flue, the smoke for connecting the primary combustion chamber and the secondary combustion chamber The center of the road is eccentric with respect to the center of the cross section of the secondary combustion chamber, the incineration material combustion exhaust gas discharged from the primary combustion chamber is introduced in the tangential direction of the secondary combustion chamber, and the exhaust gas from the secondary combustion chamber is introduced. An incinerator characterized in that a rectifying plate having an opening smaller than a cross section of the secondary combustion chamber is installed near the discharge port. 2. The opening of the current plate is substantially circular, and the opening area a is the cross-sectional area A of the secondary combustion chamber.
The incinerator is characterized by having a ratio a / A of 0.15 to 0.5. 3. The inflow velocity V (m / s) of the incinerator combustion exhaust gas into the secondary combustion chamber, the secondary combustion chamber diameter D (m), and the incinerator combustion exhaust gas kinematic viscosity ν (m2 / s). 4. The incineration method according to claim 1, wherein the dimensionless number R (DV / ν) defined is 20,000 or more.